The present invention relates generally to printing presses and more particularly to a blanket cylinder including an integrated compressible layer.
Offset lithographic printing presses, for example, have a plate cylinder and a blanket cylinder for transferring images from a printing cylinder to a web of material, such as paper.
The circumferential surface of the blanket cylinder is typically covered with a multi-layer compressible blanket having an outer print layer which receives the images from the printing plate and transfers them onto the web of material. The blanket may be a flat material wrapped around and secured to the blanket cylinder, or, in the case of gapless printing presses, it may be a sleeve-shaped material for slipping over one end of the blanket cylinder.
Printing blankets in the prior art include a print layer, a layer of reinforcing cord, a compressible layer, a base cord, and a sleeve which contacts a metal circumferential surface of the blanket cylinder. A blanket is typically between about 0.050 inches and about 0.100 inches thick. Sleeve-shaped blankets having this construction can be especially bulky to ship and store. Their multi-layer construction makes them difficult to manufacture and expensive. Also, current multi-layer blankets lose pliancy (i.e. stiffness) and gage (i.e. diameter) over time due to degradation of the matrix material, especially the compressible material. Once the printing blankets degrade sufficiently, they are disposed of, and a new blanket is mounted to the blanket cylinder. In the past, attempts have been made to overcome some of these deficiencies by adjusting the geometry and material properties of the compressible layer.
U.S. Pat. No. 4,327,467 relates to an inflated shell structure for use with other types of industrial rollers, such as curing, embossing or film winding rollers having a rubber cover wrapped around the roller. According to the shell structure of the '467 patent, a rubber tube is spirally wound around a mandrel and kept in place by an adhesive. A multi-layer bridge composite is adhesively mounted to the outside of the ruber tube. At least two layers of the bridge composite includes wire cords and the cords in at least one layer are axially aligned with the mandrel. A thin rubber cover covers the outside surface of the multi-layer bridge composite. An inflation means inflates the tube and maintains the tube under pressure.